The present invention relates to a disc clamp mechanism for preventing a disc from slipping and/or loosening from the turntable when the compact disc (e.g., DVD-ROM or CD-ROM) is on a turntable rotating at a high speed.
Traditionally, a disc-clamping device employs an elastic O-ring or a coil spring to compress steel balls for clamping a disc as shown in FIGS. 1A-1B, in which FIG. 1A is a top view and FIG. 1B is a cross-section, of the related art disc-clamping device respectively. As shown, an O-ring 14 is provided on the periphery of an axis 12 of a turntable 10. A number of (e.g., 3) steel balls 18 are equally distributed on a joining periphery of a guide member 16 and the turntable 10. The guide member 16 guides the disc (not shown) already put on the turntable 10 to press the steel balls 18 which in turn press the O-ring 14 inwardly. After the disc is completely inserted onto the axis 12 of the turntable 10, the O-ring 14 again pushes the steel balls 18 to their original positions. As such, the disc is fixedly maintained on the turntable 10. However, a loosening condition is possible due to the insufficient clamping force exerted on the disc by the O-ring 14 and the steel balls 18. This is because the O-ring 14 and the steel balls 18 are not perfectly matched in size, i.e., an undesirable gap exists between the O-ring 14 and the steel balls 18 due to unperfect machining.
Another related art using a lever member as a disc clamp mechanism is disclosed in U.S. Pat. No. 5,774,445 as shown in FIGS. 2A-2B. In FIG. 2A, a disc 20 related to being inserted into a raised portion 22 of a turntable 10a by a disc-clamping device is shown. The disc 20 is pressed by a rotational force of the turntable 10a which in turn exerts a downward force on the turntable 10a. Consequently, the disc 20 is guided to a position between a clamping hook 24 and the turntable 10a by the clamping hook 24. Thereafter, the clamping hook 24 is pushed upwardly, thereby urging the disc 20 against the turntable 10 by the clamping hook 24 to fix the disc 20 as shown in FIG. 2B. The related art is without the drawback of insufficient clamping force exerted on the disc 20. However, this is unsatisfactory due to a problem arose from the radial positioning of the disc 20. In brief, the center holes of the discs 20 are not exactly the same size when manufactured. To the worse, tolerances of the center holes are not totally offset by the level member. As a result, it is difficult to get a precise radial positioning and, therefore, to be used with the DVD products that require a high precision positioning.
Thus, it is desirable to provide a disc clamp mechanism to overcome the above drawbacks of related art, and to be, therefore, suitable for use with CD-ROM and DVD ROM products.
It is therefore an object of the present invention to provide a compact disc clamp mechanism for affixing the compact disc which has a center hole. The mechanism includes a turntable having a raised hollow axis; a positioning member sized to the center hole of the disc having a hole for being mounted on the raised hollow axis and an inclined surface; a helical spring mounted within the positioning member for providing the upward or downward movement of the positioning member along the raised hollow axis; a cylindrical disc-clamping member sized to the center hole of the compact disc having a plurality of circumferential raised portions, a plurality of slit-like recessed portions each extending from the raised portion, and a plurality of V-shaped members surrounded by two slit-like recessed portions and one of the raised portions for bending from a first predetermined position to a second predetermined position when a force is exerted thereon; and an elastic plane-like member mounted on the positioning member for enhancing the restoration force of the deformed raised portions. As such, the compact disc is secured by the raised portions, the inclined surface, and the turntable when loaded onto the disc-clamping member. The compact disc clamping mechanism of the present invention find particularly useful applications in DVD-ROM products which require a relatively high precision.
It is another object of the present invention to provide a compact disc clamp mechanism for fixing the compact disc having a center hole comprising a turntable having a raised hollow axis; a cylindrical disc-clamping member sized to the center hole of the compact disc mounted on the raised hollow axis having a plurality of raised portions in circumference, a plurality of slit-like recessed portions each extending from the raised portion, and a plurality of V-shaped members surrounded by two slit-like recessed portions and a raised portion for bending from a first predetermined position to a second predetermined position when a force is exerted thereon; and an elastic plane-like member mounted within the disc-clamping member for enhancing the restoration force of the deformed raised portions. As such, the compact disc is secured by the raised portions and the turntable when loaded onto the disc-clamping member. This compact disc clamp mechanism finds a particular application in the CD-ROM products which require a relatively low precision.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.